Combination stiff and flexible golf club shaft

ABSTRACT

A golf club haVing a shaft construction that inhibits rearward flexing of the shaft at the top of the back swing and initial part of the down swing while permitting forward flexing through the ball on the down swing. A rearwardly facing side of a wall of the shaft is formed of a plurality of sections that extend longitudinally along the shaft and that have proximately located facing ends.

[111 3,764,137 [451 Oct. 9, 1973 2,992,828 7/1961Stewart.....................,.....,. 273/80 B FOREIGN PATENTS ORAPPLICATIONS COMBINATION STIFF AND FLEXIBLE GOLF CLUB SHAFT Anthony J.Petro, Box 338, Dippel Manor, Pa. 18201 June 9, 1972 9,625 4/1914 GreatBritain 273/80 B [76] Inventor:

Primary Examiner-Richard C. Pinkham Assistant Examiner-Richard J. ApleyAttorney-D. Paul Weaver et al.

[22] Filed:

[21] Appl. No.: 261,547

ABSTRACT [52] U S Cl 273/80 B v I [51] Int. A631) 53/12 A golf clubhavmg a Shaft C(mstrucnon that mhlblts 58 Field of Search 273/77 R, 80R, 80 B, rearward flexing of the Shaft at the p of t back 273/81 R 193R, 194 R, 3 R, 2 R swing and initial part of the down swing whilepermitting forward flexing through the ball on the down swing. Arearwardly facing side of a wall of the shaft is formed of a pluralityof sections that extend longitudinally along the shaft and that haveproximately located facing ends.

1 mm 30 LS PATENTED OUT 9 FIG. 2

/III I FIG. 4

FIG. .9

FIG. 8

COMBINATION STIFF AND FLEXIBLE GOLF CLUB SHAFT BACKGROUND OF THEINVENTION ball, the farther it will go. The kinetic energy is equal toone-half of mass times velocity squared. In using a golf club to drive agolf ball it is therefore desired to impart as much velocity as'isfeasible to the club head.

Presently, golf club shafts are designed in different thicknesses tothus vary the shaft stiffness. Golfers select shaft stiffness dependingon their strength or ability to swing the club head forwardly againstthe ball against the resistance presented by the shaft rigidity.

A relatively strong golfer will select a relatively stiff shaft due tohis having the strength in his hands to overcome the resistance of theshaft to forward flexing as the club head engages the ball.

A relatively weak golfer must necessarily use a more flexible shaft sothat the shaft will flex forwardly during the down swing to increase thehead velocity at the moment of impact of the head with the ball.However, with a flexible shaft, there is also a rearward flexing of theshaft at the end of the back swing and at the beginning of the downswing. Ifa golfer swings too fast with a flexible shaft, there is alarge rearward head displacement at the end of the back swing and at thebeginning of the down swing so that the club head will be rearwardlydisplaced by the bending of the shaft during the initial part of thedown swing if the speed of the down swing is too great. Therefore, witha flexible shaft, a golfer must swing slower than he is able toin orderto minimize rearward head displacement and allow the head to squareitself on impact with the ball. As a result, although it is easier toswing a flexible shaft from a strength standpoint, the necessity of aslower swing reduces the velocity of the club head at the moment ofimpact of the head with the ball to thus reduce the distance the hitball will travel.

SUMMARY OF THE INVENTION The object of this invention is to provide agolf club shaft construction which will inhibit rearward displacement'ofthe golf club head by minimizing rearward shaft flexing and will,nevertheless, permit easier forward head movement through the impactzone to provide for the increased velocity of the head at the mo-- Iminimizes shaft flexing rearwardly. Through the impact zone, theproximate section ends move away from each other to permit the shaft toflex forwardly.

While the prior art, as illustrated by US. Pat. Nos. 2,078,728 and2,220,852 show golf club shafts having sections with facing endsextending longitudinally of the shaft, these sections are not so locatedas to' solely face rearwardly of the shaft for the purpose of thisinvention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevation of the golfclub;

FIG. 2 is a section of a part of the golf club shaft;

FIG. 3 is a view taken on the line 3-3 of FIG. 2;

FIG. 4 is a section taken on the line 4-4 of FIG. 3;

FIG. 5 is a section similar to FIG. 2, but showing the shaft while it isflexing forwardly;

FIG. 6 is a section similar to FIG. 4, but showing the 0 sections asbeing mounted on the rearwardly facing side of thefront portion of atubular shaft; and

FIGS. 7 through 9 are views of different species of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. I shows a golf club I0having a head 12 and a grip 14 that are separated by a resilient shaftI6. The shaft 16, as is conventional, is formed of a hollowtubularmember. The front of the shaft is considered to be that side of theshaft that faces toward the golf ball when the golf club is suwngtowards the ball and the back of the shaft is considered to be that sideof the shaft that faces away from the golf ball when the golf club isswung towards the golf ball.

Referring to FIGS. 24, the shaft I6 has a substantially uniform wallthickness. A plurality of metal sections 18 extend longitudinally alongthe shaft l6 on the rearwardly facing side of the back portion of theshaft 16 and are secured thereto as, for example, by being bondedthereto. In the unflexed condition of the shaft 16, the facing ends ofthe sections 18 are parallel to each other and are proximately locatedby either being spaced very close to each other or by abutting eachother.

rearwardly facing or back side of the shaft exterior periphery is undercompression and the adjoining edges of the sections 18 are forcedagainst each other to thus minimize rearward flexing of the shaft 16.However, when the club head is entering the impact zone on the downswing, the rearwardly facing or back side of the shaft goes into tensionand the shaft may flex more easily forward, as indicated in FIG. 5, withthe adjoining ends of the sections 18 separating from each other.

Since the lower part of the shaft 16 has the maximum flexing duringthedown swing, and since in certain circumstances, it would be desirablenot to'add an undue amount of weight to the shaft, the metal sections 18preferably extend along the lower one-half to one-third of the shaft asindicated in FIG. I. For the same reason, the sectionsl8 are preferablymade smaller as theyextend downwardly of the shaft 16, as shown in FIG.3. In view of the foregoing, it can be seen that the shaft 16 withattached sections 18 is rigid or stiff against rearward flexing so thatthe head I2 will only deflect minimally rearwardly with respect to aplane lengthwise through the grip 14 of the club at the end of the backswing and the beginning of the down swing. However, through the impactzone on the down swing, the head 12 will swing more readily forwardlyrelative to the plane through the grip 14 to thus increase the velocityof the head at the moment of impact with the ball and thereby impartincreased energy to the ball to thus increase the travel distance of thehit ball. Since the head deflects less with respect to the plane throughthe When the shaft tends to bend backwards at the top of the back swingand initial part of the down swing, the

grip on rearward shaft flexing, the golfer will not have to deliberatelyswing slower during the down swing to wait for the head to move from itsrearwardly deflected position relative to the grip of the club.

Instead of mounting the sections 18 to the rearwardly facing exterior ofthe back portion of the shaft 16, the same effect may be accomplished asshown in FIG. 6 by mounting the sections 18 to the rearwardly facingside of the front portion of the tubular shaft 16 on the inner peripheryof the shaft.

FIG. 7 shows a tubular golf club shaft 20 wherein the back shaft portion22 (the portion facing away from the golf ball during the down swing) ismade thicker than the front shaft portion 24. A series of thin slits 26are formed in the rearwardly facing side of the back portion 22 that arespaced lengthwise of the shaft and lie in planes that are at rightangles to the shaft axis. The slits 26 separate the rearwardly facingside of the shaft back portion into sections 27 that function similarlyto the sections IS in rendering the shaft rigid or stiff during rearwardflexing and in rendering the shaft flexible during forward flexing.

As shown in FIG. 7A, this same concept is attainable wherein the frontshaft portion 24' (the portion facing toward the golf ball during thedown swing) of a tubular golf club shaft 20' is made thicker than theback shaft portion 22'. A series of thin slits 26' are formed in therearwardly facing side of the front portion 24' that are spacedlengthwise of the shaft and lie in planes that are at right angles tothe shaft axis. The slits 26' separate the rearwardly facing side of theshaft front portion into sections 27' that function similarly tosections 18 in.

rendering the shaft rigid or stiff during rearward flexing and inrendering the shaft flexible during forward'flexmg.

In arrangements discussed above, the shaft is rendered rigid againstrearward flexing due to an increase in the compressive strength of arearwardly facing side of the shaft. While these arrangements may alsoslightly increase the tensile strength of said shaft side, they do notdo so to such an extent as to materially inhibit the flexibility of theshaft through the impact zone. In order to increase the compressivestrength of a rearwardly facing side of the shaft without increasing itstensile strength, the arrangements of FIGS. 8 and 9 may be provided. Inthese Figures, metal sections 28 (FIG. 8) or 30 (FIG. 9) extend at least180 about the periphery of the shaft 16 and are fastened along the axialcenterline of the shaft to the shaft periphery by fasteners 32. As inthe arrangement of FIG. 2, the facing edges of the sections 28 and 30are either close to eace other or abut each other in the unflexedcondition of the shaft I claim:

I. In a golf club having a shaft extending between a head and a grip,the head being adapted to hit a golf ball while moving forwardly duringa down swing that is imparted to the club while it is being held by thegrip after the club has been moved through a back swing; said shaftcomprising: a plurality of adjacent sections located exclusively on arearwardly facing side of said shaft and extending longitudinally ofsaid shaft, an end of each of said sections facing an end of anadjoining section, said plurality of sections constituting means on saidshaft whereby said ends are proximate to each other in an unflexedcondition of said shaft, forced against each other during a back swingand the initial part of the down swing thereby inhibiting rearwardflexing of said shaft, and spaced apart from each other during thelatter part of the down swing thereby allowing forward flexing of saidshaft 2. The golf ball club of claim I wherein the shaft is tubular andwherein the sections are on the rearwardly facing side of the backportion of the shaft.

3. The golf club of claim I wherein the shaft is tubular and wherein thesections are on the rewarwardly facing side of the front portion of theshaft.

4. The golf club of cairn 1 wherein a plurality of rearwardly facingslits intersecting the shaft periphery are formed in the rearwardlyfacing side of the shaft to thus form said sections.

5. The golf club of claim 4 wherein the shaft is tubular and wherein theback portion of the shaft, containing the slits, is thicker than thefront portion of the shaft.

6. The golf club of claim 4 wherein the shaft is tubular and wherein thefront portion of the shaft, containing the slits, is thicker than theback portion of the shaft.

7. The golf club of claim I wherein said sections extend at least aboutthe periphery of the shaft and are fastened to the shaft periphery alongthe longitudinal centerline of the shaft.

8. The golf club of claim I wherein said sections extend along the lowerpart of the shaft.

9. The golf club of claim I wherein said sections are made of metal andare bonded on said shaft.

10. The golf club of claim I wherein said sections are progressivelysmaller as they extend downwardly of said shaft.

11. The golf club of claim 10 wherein said sections extend along thelower part of the shaft.

1. In a golf club having a shaft extending between a head and a grip,the head being adapted to hit a golf ball while moving forwardly duringa down swing that is imparted to the club while it is being held by thegrip after the club has been moved through a back swing; said shaftcomprising: a plurality of adjacent sections located exclusively on arearwardly facing side of said shaft and extending longitudinally ofsaid shaft, an end of each of said sections facing an end of anadjoining section, said plurality of sections constituting means on saidshaft whereby said ends are proximate to each other in an unflexedcondition of said shaft, forced against each other during a back swingand the initial part of the down swing thereby inhibiting rearwardflexing of said shaft, and spaced apart from each other during thelatter part of the down swing thereby allowing forward flexing of saidshaft.
 2. The golf club of claim 1 wherein the shaft is tubular andwherein the sections are on the rearwardly facing side of the backportion of the shaft.
 3. The golf club of claim 1 wherein the shaft istubular and wherein the sections are on the rearwardly facing side ofthe front portion of the shaft.
 4. The golf club of claim 1 wherein aplurality of rearwardly facing slits intersecting the shaft peripheryare formed in the rearwardly facing side of the shaft to thus form saidsections.
 5. The golf club of claim 4 wherein the shaft is tubular andwherein the back portion of the shaft, containing the slits, is thickerthan the front portion of the shaft.
 6. The golf cluB of claim 4 whereinthe shaft is tubular and wherein the front portion of the shaft,containing the slits, is thicker than the back portion of the shaft. 7.The golf club of claim 1 wherein said sections extend at least 180*about the periphery of the shaft and are fastened to the shaft peripheryalong the longitudinal centerline of the shaft.
 8. The golf club ofclaim 1 wherein said sections extend along the lower part of the shaft.9. The golf club of claim 1 wherein said sections are made of metal andare bonded on said shaft.
 10. The golf club of claim 1 wherein saidsections are progressively smaller as they extend downwardly of saidshaft.
 11. The golf club of claim 10 wherein said sections extend alongthe lower part of the shaft.